Effects of apocynin on phenylephrine-induced RhoA membrane translocation. RTA strips were pre-incubated with apocynin or vehicle for 30 min and then challenged with phenylephrine for 1 min (a) or 15 min (b). The cytosolic and membrane fractions were separated by ultracentrifugation and RhoA in each fraction were analyzed by immunoblotting as described in Methods. The top panels show representative immunoblots. The bottom panels summarize the quantitative results, expressed as the ratio of membrane RhoA to total RhoA, from six independent experiments. The bars represent means ± S.E.M.. *p < 0.05 vs. control; #p < 0.05 vs. phenylephrine alone.